Renault is confident the major issues it experienced at the first test are solved and that it now has a good baseline for its new power unit to build on.

Renault struggled with a number of issues at the opening pre-season test at Jerez, including a serious problem with its battery that limited the mileage its teams were able to complete in the opening days of the test. The engine supplier has been working flat out to solve the problems since Jerez and, despite problems for Renault-powered cars on the opening day of this week's Bahrain test, head of track operations Remi Taffin is confident his engineers have made good progress.

"We can clearly say today we can run our power unit as we wanted," he said. "It is still not to the level we want but at least we have got the baseline to work from. From tomorrow onwards we will be upgrading things and it will be like this until the end of next week. So we are happy on that side but obviously we also had some problems, which are under the table.

"When we have some time to run we will have some new problems, although they will not be as big as we had two weeks ago, but we will still have to fix them. That is why we will see some cars running or not, some less or more. That's where we are: on plan but still recovering."

During the week, Red Bull chief technical officer Adrian Newey said the Renault power unit "seems to have a particularly large cooling requirement", but Taffin denied the turbo engine and energy recovery systems have inherent cooling issues.

"I don't think we are that bad, to be fair. We are trying our best on this side. Let's put it this way, we didn't have any heating problems here. Obviously it's not that hot but we can translate it to other races and we are not in that bad a shape. We are quite happy on this side."

FIA regulations require the engines to be homologated at the end of the month, giving engine suppliers just nine days to finalise some aspects of the power units, but Taffin is confident Renault can reach that target.

"If I was saying everything is solved I would be lying, but I think by the end of the month we will have a specification that we will be happy with to go to Melbourne."